Reverse electron flow: Difference between revisions

Latest revision as of 16:55, 29 December 2024

Biochemical process in cellular respiration

Reverse electron flow is a biochemical process that occurs in certain microorganisms and is part of their metabolic pathways. This process is essential for the generation of reducing power in the form of NADH or NADPH, which are crucial for various biosynthetic reactions.

Mechanism[edit]

In reverse electron flow, electrons are transferred from a donor with a lower reduction potential to an acceptor with a higher reduction potential, against the thermodynamic gradient. This process requires the input of energy, which is typically derived from the proton motive force generated by the electron transport chain.

The reverse electron flow is often observed in chemolithoautotrophs, which are organisms that obtain energy by oxidizing inorganic substances. These organisms use reverse electron flow to generate NADH from NAD+ when the direct reduction of NAD+ is not thermodynamically favorable.

Biological Significance[edit]

Reverse electron flow is significant in the carbon fixation pathways of certain bacteria, such as the Calvin cycle in cyanobacteria and some purple bacteria. It allows these organisms to assimilate carbon dioxide into organic compounds, which is vital for their growth and survival.

Examples[edit]

One example of reverse electron flow is found in the sulfur-oxidizing bacteria, where electrons from the oxidation of sulfur compounds are used to reduce NAD+ to NADH. Another example is in the nitrifying bacteria, which oxidize ammonia to nitrite and use reverse electron flow to generate reducing power for carbon assimilation.

References[edit]

External links[edit]

Reverse Electron Flow on WikiMD

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-== Reverse Electron Flow ==
-[[File:Reverse Electron Flow Diagram.png|thumb|Diagram illustrating the process of reverse electron flow]]
+{{Short description|Biochemical process in cellular respiration}}
+{{Infobox biochemical pathway
+| name = Reverse Electron Flow
+| image =
+| caption =
+| map =
+| map_caption =
+| map_size =
+| EC_number =
+| CAS_number =
+| GO_code =
+}}
-'''Reverse electron flow''' (also known as '''reversed electron transport''' or '''RET''') is a process in [[microbiology]] and [[biochemistry]] where electrons are moved against their electrochemical gradient across a [[biological membrane]]. This process is primarily observed in [[prokaryotic]] organisms, such as [[bacteria]] and [[archaea]], and is a key component of their [[metabolism]].
+'''Reverse electron flow''' is a biochemical process that occurs in certain [[microorganisms]] and is part of their [[metabolic pathways]]. This process is essential for the generation of [[reducing power]] in the form of [[NADH]] or [[NADPH]], which are crucial for various [[biosynthetic reactions]].
-== Overview ==
-In normal [[electron transport chain]] (ETC), electrons move from a high energy state to a lower one, releasing energy that is used to pump protons across a membrane, creating a [[proton gradient]]. This gradient is then used to generate [[adenosine triphosphate]] (ATP), the energy currency of the cell, through a process known as [[oxidative phosphorylation]].
-In reverse electron flow, the process is essentially reversed. ATP is used to pump protons across the membrane, creating an electrochemical gradient that drives electrons to move from a low energy state to a higher one. This process is used by certain organisms to generate reducing power in the form of [[reduced nicotinamide adenine dinucleotide]] (NADH) or [[reduced nicotinamide adenine dinucleotide phosphate]] (NADPH).
 == Mechanism ==
+In reverse electron flow, electrons are transferred from a donor with a lower [[reduction potential]] to an acceptor with a higher reduction potential, against the thermodynamic gradient. This process requires the input of energy, which is typically derived from the [[proton motive force]] generated by the [[electron transport chain]].
-[[File:Mechanism of Reverse Electron Flow.png|thumb|Mechanism of reverse electron flow]]
+The reverse electron flow is often observed in [[chemolithoautotrophs]], which are organisms that obtain energy by oxidizing inorganic substances. These organisms use reverse electron flow to generate NADH from NAD+ when the direct reduction of NAD+ is not thermodynamically favorable.
-The mechanism of reverse electron flow varies among different organisms, but generally involves the following steps:
+== Biological Significance ==
+Reverse electron flow is significant in the [[carbon fixation]] pathways of certain bacteria, such as the [[Calvin cycle]] in [[cyanobacteria]] and some [[purple bacteria]]. It allows these organisms to assimilate carbon dioxide into organic compounds, which is vital for their growth and survival.
-# ATP is hydrolyzed to pump protons across the membrane, creating a proton gradient.
+== Examples ==
-# The proton gradient drives the movement of electrons from a low energy state to a higher one.
+One example of reverse electron flow is found in the [[sulfur-oxidizing bacteria]], where electrons from the oxidation of sulfur compounds are used to reduce NAD+ to NADH. Another example is in the [[nitrifying bacteria]], which oxidize ammonia to nitrite and use reverse electron flow to generate reducing power for [[carbon assimilation]].
-# The high-energy electrons are used to reduce NAD+ or NADP+ to NADH or NADPH, respectively.
-== Significance ==
+== See also ==
+* [[Electron transport chain]]
+* [[Proton motive force]]
+* [[Chemolithoautotrophy]]
+* [[Carbon fixation]]
-Reverse electron flow is significant in several ways:
+== References ==
+{{Reflist}}
-# It allows organisms to generate reducing power in the form of NADH or NADPH, which are essential for various metabolic processes, including [[anabolism]] and [[biosynthesis]].
+== External links ==
-# It enables certain organisms to survive in environments with limited nutrients or energy sources.
+* [https://www.wikimd.com/wiki/Reverse_electron_flow Reverse Electron Flow on WikiMD]
-# It provides a mechanism for the regulation of cellular metabolism and energy balance.
-== See Also ==
-* [[Electron transport chain]]
-* [[Oxidative phosphorylation]]
-* [[Proton gradient]]
-* [[Adenosine triphosphate]]
-* [[Reduced nicotinamide adenine dinucleotide]]
-* [[Reduced nicotinamide adenine dinucleotide phosphate]]
+[[Category:Biochemistry]]
+[[Category:Metabolic pathways]]
 [[Category:Microbiology]]
-[[Category:Biochemistry]]
 [[Category:Cellular respiration]]
-[[Category:Metabolism]]